There exists a substantial need for various particles which are suitable for use as supports for different adsorbent groups in the field of chemistry, in general in connection with chromatography, and in particular in connection with immuno-absorption therapy. Such supports which have a large active surface and which can be rapidly and effectively brought into equilibrium with a flowing medium and also offer a low flow resistance thereto are especially desirable in this context. A support which presents such properties may consist of a solid inner core which has only small pores, or preferably none at all, which is coated with a thin layer of a gel which acts as a bonding medium for such adsorbent groups.
Columns which contain solid supports with immuno-adsorbents immobilized thereon are found, for example, in U.S. Pat. Nos. 4,180,383 and 4,215,688. In at least the above-mentioned '383 patent, there is described a support which consists of an inner solid core with one or more outer layers of active material. However, the description of how these outer layers is produced is quite inadequate in this patent. It is therefore an object of the present invention to provide a method for the manufacture of such supports and more particularly to solid cores coated with hydrophilic gels.